JPH054965B2 - - Google Patents

Abstract

1. Impregnation materials consisting of unsaturated polyesters and acryloyl and/or methacryloyl compounds as reactive diluents and optionally conventional additives, characterised in that they contain a) hexanediol diacrylate and/or b) butanediol diacrylate as reactive diluents and in that the viscosity of the impregnation materials is at the most 1500 mPa . s.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to impregnating resin compositions based on unsaturated polyester resins and copolymerizable monomeric acrylic and/or methacrylic compounds. Such impregnating resin compositions can be used for insulating electrical windings such as motors, transformers and generators.

The impregnating resin compositions of the above-mentioned method are used extensively in industry and are used inter alia in DE-A series.
No. 1570273 and No. 2856050. However, the impregnating resin compositions used in practice contain only styrene as a copolymerizable monomer compound (so-called reactive diluent). Although it is mentioned in the said publication that acrylic and/or methacrylic compounds may also be used as reactive diluents, no examples are given, and no examples are given of these reactive diluents instead of styrene. There are no commercial products that do this. The reason is that it is believed that sufficient impregnation of the electrical winding cannot be achieved since the resin composition for impregnation has a high viscosity.

Although the use of styrene as a reactive diluent produces a sufficiently low viscosity impregnating resin composition,
However, it is associated with many drawbacks. Most of the styrene is removed by evaporation during the thermosetting period;
Thus it is lost. Styrene loss is approximately 15-30% by weight based on the impregnating resin composition used for impregnation. The smell of styrose is very unpleasant. This is physiologically dangerous and according to the Industrial Air Directive of the Federal Republic of Germany (Technische
It belongs to the class of hazardous substances according to Anweisung Luft. Styrene-containing impregnating resins also have the disadvantage that they weaken the insulation of painted wires to a certain extent, which results in the formation of cracks in the insulation of painted wires and, in practical use, reduces the insulation of the insulation system. This could lead to further deterioration.

The present invention has relatively low evaporation losses and is at least physiologically less hazardous than styrene-containing impregnating resin compositions, but the penetration of the impregnated winding is more intense and therefore results in a better impregnating effect. It is based on the problem of finding a resin composition for impregnation.

DE-A No. 1570273 and the above-mentioned DE-A No.
2856050, an attempt was made to prepare an impregnating resin composition based on an unsaturated polyester resin and an acrylic and/or methacrylic compound, in which hydroxypropyl methacrylate (HPMA), butanediol dimethacrylate (BDDMA) and neopentyl glycol dimethacrylate were used. It has been found that the use of conventional compounds such as methacrylate (NPG-DMA) alone results in corresponding impregnating resin compositions with unhelpful properties. It has surprisingly been found that when certain acrylates are used, the aforementioned disadvantages of styrene-containing impregnating resin compositions are avoided and, moreover, unexpected advantages are obtained as described in detail below.

Therefore, the present invention contains a hexanediol diacrylate and/or b butanediol diacrylate as the reaction diluent, and the viscosity of the impregnating resin composition is the highest.
The present invention relates to an impregnating resin composition based on an unsaturated polyester and an acrylic and/or methacrylic compound as a reactive diluent, characterized in that it has a pressure of 1500 mPa·s.

The invention also relates to a method, characterized in that an impregnating resin composition as defined above is used for insulating the winding wire by impregnating the winding with the impregnating resin composition.

According to the invention, therefore, as acrylate a hexanediol diacrylate (HDDA)
and/or b It is essential that butanediol acrylate (BuDA) is used.

The amount of acrylate is adapted to the degree of unsaturation of the unsaturated polyester according to the knowledge of those skilled in the art. It is used for large deficiencies or small excesses. However, it is not necessary to use large excesses as is customary in styrene. This is because, as mentioned above, a considerable amount of styrene is removed by evaporation during aging and hardening of the impregnated coil. Even if they can be used in short quantities as mentioned above, this is often not for the purpose. This is because all unsaturations of the unsaturated polyester are preferably cross-linked by acrylates and methacrylates. Since the evaporation losses according to the invention do not reach 5%, mostly 2% by weight of said acrylate, based on the amount required for complete cross-linking of the unsaturations, the impregnating resin composition according to the invention It is preferred not to have any excess of acrylates and methacrylates, such as limited to 5% by weight, preferably 2% by weight. If an insufficient amount is used, it should not be less than 10% by weight, preferably not less than 5% by weight, corresponding to the above definition for the reasons mentioned above.

Another important indicator of the resin composition for impregnation according to the present invention is its viscosity of up to 1500 mPa・s at 25°C.
It is to be. In that case, a viscosity that is considerably higher than the viscosity of the impregnating resin compositions based on styrene as reactive diluents on the market is essential.
These have viscosities ranging from about 100 to 500 mPa·s. With such a high viscosity, as the impregnating resin composition according to the invention may have, penetration of the windings can be achieved, with the mechanical and electrical properties in the insulation system being comparable to conventional methods or The superiority over that which can be achieved with state-of-the-art styrene-containing impregnating resin compositions is particularly surprising.

According to a preferred embodiment of the invention, the impregnating resin composition comprises c) hydroxypropyl methacrylate (HPMA) and/or d) butanediol monoacrylate (BDMA) in an amount of up to 10% by weight, based on the total amount of acrylates and methacrylates. It may additionally be included. The addition of these mono(meth)acrylates reduces the viscosity but does not improve any other insulation properties. The amount of these mono(meth)acrylates should therefore be as low as possible, preferably below 5% by weight. Significant reductions in viscosity are already obtained in amounts of 1% by weight and above. Surprisingly, however, it is not possible to obtain impregnating resin compositions that are usable or have properties that are superior to conventional methods solely by the use of acrylates c) and/or d).

According to another embodiment of the invention, the impregnating resin composition advantageously additionally contains tri(meth)acrylate in the same amount as mentioned above for the monoacrylate.
Contains acrylate. The addition of triacrylates has the surprising effect of improving the mechanical properties, such as the baking value according to DIN 46448 of age-hardened impregnating resin compositions. Suitable tri(meth)acrylates are pentaerythritol triacrylate, pentaerythritol trimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate.

The impregnating resin composition according to the invention is based on the known compounds used for this purpose as unsaturated polyester resins, in particular the so-called imide-containing compounds as described in DE-A 1570237, DE-A 1770386 and DE-A 2856050. May contain saturated polyester. However, it is also possible to use so-called imide-free polyesters, as have been known for many years. These unsaturated polyesters are condensation products obtained from polyhydric carboxylic acids, polyhydric alcohols, and, if they contain imides, amino group-containing compounds, optionally with some monofunctional compounds. Examples of polyhydric carboxylic acids are optionally saturated or aromatic carboxylic acids such as succinic acid or adipic acid, phthalic acid, isophthalic acid, terephthalic acid, etc. as well as tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid or the corresponding partially or fully halogenated acids. dicarboxylic acids, such as maleic acid or phallic acids, citraconic acid, itaconic acid, mixed with chemical compounds (having anti-inflammatory properties).
Examples of compounds with various functional groups are citric acid, monoethanolamine, aminoethanecarboxylic acid and the corresponding aminoalcohols or aminocarboxylic acids containing 3 or 4 CH ₂ groups. These acids can be used as esters, half-esters or anhydrides. As compounds containing hydroxyl groups it is likewise possible in principle to use the compounds which are used for the preparation of polyesters by conventional methods. Suitable diols are, for example, glycols, neopentyl glycol, propylene glycol. Polyols having 3 or 4 hydroxy groups are, for example, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, trihydroxyethyl isocyanurate. The imide-containing unsaturated polyester is advantageously combined with condensed tetrahydrophthalic acid or with amino groups.
Contains its anhydride which constitutes a membered imide ring. The polyesters may also contain monofunctional carboxylic acids, alcohols and/or amines as chain interrupters. They may also contain saturated and unsaturated oils, for example hydroxy-functional oils such as castor oil, or carboxy-functional oils such as maleinate oil.

The impregnating resin composition according to the invention also contains customary additives such as pigments, diluents, plasticizers, catalysts (e.g. peroxides), promoters (e.g. metal salts), stabilizers (e.g. hydroquinone, benzoquinone). I can do it.

The impregnating resin composition according to the invention can also contain small amounts of styrene or allyl compounds, such as diallyl phthalate, in order to obtain special effects, in which case their amount depends on the weight of the acrylate contained in the impregnating resin composition. should not exceed 10% by weight.

For example, the following method can be used to use the impregnating resin composition for impregnating electric windings.

Immersion Impregnation In this method, the material to be impregnated is immersed in the impregnating resin composition for a certain period of time, determined by preliminary tests, or introduced into the impregnating resin in a transfer operation. Curing of the impregnated resin is then carried out at 120-170° C. for 1-5 hours in a fixed or transitional oven.

Vacuum Impregnation When using this method, the material to be impregnated is first placed in a vacuum container and then a vacuum is applied.

Once the desired vacuum is obtained, the impregnating agent is fed from the storage container to the vacuum kettle. In this case, it is not the very long retention of the vacuum that is decisive for the impregnation quality;
This is the length of venting time during which the pressure created by stopping the vacuum forces the impregnating agent into the remaining voids.

Here, in order to perform more quickly, overpressure can also be used after vacuum. For a small number of objects that are very difficult to impregnate, the vacuum pressurization method is indispensable.

Curing is accomplished as described in the dipping method.

Drop Impregnation In contrast to the methods described so far, the object is not immersed in the impregnating agent during dripping, but this is applied to the rotating winding using a nozzle.

In order to ensure good penetration of the resin into the windings, it is necessary to preheat the object that is to receive the drop. This can be accomplished by induction heating or by warming in a pre-connected oven. Since the resin used here has a very short gelation time (approximately 5-8 minutes at 100 °C and at least 14 minutes at 100 °C for the impregnated resin), the temperature may not be sufficient in the dropwise step to cause premature gelation of the resin. Temperatures should not exceed 95℃ to prevent The object is then further rotated and heated to approximately 130°C and 15°C depending on the resin adjustment.
Allow to cure for ~30 minutes.

Immersion impregnation with rotational hardening This method is mainly applied in large heavily loaded rotors and stators. The object is conventionally dipped into the impregnating agent (possibly using a vacuum) and then placed in a curing oven on a rotating field or rollers.

Curing is carried out at 120-170°C for 2-6 hours.

Production example of unsaturated polyester (UP) Production example 1 In a reaction vessel equipped with a thermometer, stirrer and cooler, 2325 g of castor oil and 600 g of maleic anhydride are heated to 130°C while stirring and introducing an inert gas. and then held at 130°C for 2 hours. In this way a crude product is obtained which is used as described below.

Monoethanolamine in a 2-volume three-necked flask equipped with a thermometer, stirrer, circulator, and condenser.
150 g and 100 ml of xylene and 372 g of tetrahydrophthalic anhydride are added in portions so that the exothermic reaction is kept under control. It is then heated to 165° C. and condensed with circulating xylene until the acid number is <3. Then maleic anhydride
73g, crude product 819g and xylene 60ml were added to this and under stirring and xylene circulation 185-190
Heat to ℃. When an acid number of about 15 is reached, the polycondensation is stopped and the xylene is distilled off under vacuum.

Production example Amount of two components (g) Neopentyl glycol 426 Propylene glycol 90 Isophthalic acid 424 Maleic anhydride 248 Xylene 114 Hydroquinone 0.14 4-volume three-necked Schliff equipped with stirrer, thermometer, water separator and condenser. ) while filling neopentyl glycol and propylene glycol into a flask and introducing an inert gas.
Heat to 100℃. Then add isophthalic acid and heat to 210° C. while stirring. The water formed during the reaction is distilled off and collected in a separator. When an acid number of about 9 is reached, the esterification reaction is stopped, the reaction product is cooled to 140°C, maleic anhydride and xylene are sequentially added and heated again to 210°C.
The reaction mixture is kept at 210° C. under xylene circulation until an acid number of 16.5 is reached. The xylene is then distilled off under vacuum, cooled to 160°C and hydroquinone (stabilizer) is added. Polyester resin has an acid value
15.0 and a viscosity of 800 mPa·s, measured at 25°C at 60% in cyclohexane.

Example 1 To the reaction mixture obtained according to Preparation Example 1, at 150° C., 2.30 g of toluhydroquinone and at about 100° C. 850 g of a hexanediol diacrylate/hydroxypropyl methacrylate (95:5) mixture are added.
The resulting acrylic solution has a solids content of 25% at a solids content of 60%.
It had a viscosity of 630 mPa·s and an acid value of 10 at °C (the solution thus obtained is acrylic solution A).

Separately, a hexanediol diacrylate/hydroxypropyl methacrylate (95:5) mixture was added to the reaction mixture obtained according to Production Example 2.
Add 830g. The resulting acrylic solution is a solid
At 55% it had a viscosity of 1550 mPa·s and an acid value of 15 at 25° C. (the solution thus obtained is acrylic solution B).

Acrylic solution in a mixing container equipped with a stirrer
Add A660g. Then acrylic solution under stirring
Add 330g of B to this. Stir until the mixture is completely homogenized. The resin composition for impregnation thus obtained had a viscosity of 800 mPa at 25°C at a solid content of 58%.
It had s. It is used for impregnating electrical winding products and when aged and cured at 130° C. for 3 hours yields an insulating coating with excellent mechanical and electrical properties. The test results according to DIN 46448 and 53505 are shown below.

Gel time at 100°C with 2% tert-butyl perbenzoate (50%) 10.0 min Baking value at 155°C 3.5 Viscosity at 25°C 800 mPa・s Shore D hardness 63±2 Curing in thick layer Upper side 111 Internal 111 Example 2 Acrylic solution in a mixing vessel equipped with a stirrer
Add 500g of A. Then acrylic solution under stirring
Add 500g of B. Stir the mixture until it is completely homogenized. The impregnating resin composition thus obtained has a viscosity of 58% solids at 25°C.
It had 1100mPa・s. It is used for impregnating electrical winding products and, after aging and curing at 130° C. for 3 hours, produces an insulating coating with excellent mechanical and electrical properties. The test results according to DIN 46448 and 53505 are shown below.

2% tert-butyl perbenzoate (50%) Gel time at 100°C using 9.0 minutes Baking value at 155℃ 3.7 Viscosity at 25℃ 1100mPa・s Shore D hardness 65±2 Curing in thick film layers Upper side 221 inside 121

Claims (1)

[Scope of Claims] 1. Contains a) hexanediol diacrylate and/or b) butanediol acrylate as a reactive diluent and has the highest viscosity.
A resin composition for impregnation based on an unsaturated polyester and an acrylic and/or methacrylic compound as a reactive diluent, characterized in that it has a pressure of 1500 mPa·s. 2 Contains a) hexanediol diacrylate and/or b) butanediol diacrylate as reactive diluent and whose viscosity is highest
1500 mPa・s, the impregnating resin composition is based on an unsaturated polyester and an acrylic and/or methacrylic compound as a reactive diluent, the acrylate and methacrylate contained in the impregnating resin composition Resin composition for impregnation, characterized in that it additionally contains c) hydroxypropyl methacrylate and/or d) butanediol monoacrylate in an amount of up to 10% by weight, based on the total amount.